The shelter for this centrally located bus and tram stop at Bohl was originally commissioned in 1989 by the City of St. Gallen Building Surveyor's Office. The first submission was for a straight-forward roof structure centered on a longitudinal tube, which cantilevered off two inclined concrete supports to carry the ribs of the glass plates. In the same year, the project was reworked by Calatrava and he introduces a glass screen system installed around the curved-cast seats in front of each support. These glass screens will be folded away during the year's warmer months and in winter, it will be repositioned around the benches to provide protection from adverse weather.
In 1994, the authorities revived the project and three new proposals were made. In the design that was eventually selected, the main structure is an arched steel truss, spanning 40 meters between a pair of chrome spindles. Steel and glass cantilevers extend 3.8 meters from this structure. The roof is completed by laminated security-glass sections laid between the cantilevers. The ends of the cantilevers are stabilized by a series of 21 steel-mullions, which define the protected side of the shelter. The main truss has a compression tube with a curve of 65 meters in radius. It has an outside diameter of 220 millimeters and a wall thickness ranging between 22 and 35 millimeters.
The tension tube has a curve of 153 meters in radius. It has an external diameter of 275 millimeters and a wall thickness between 16 and 30 millimeters. To ensure geometric accuracy, the bowed, suspended roof was factory-made, with the halves being joined on site. The maximum clearance of the arch is 3.5 meters; the minimum clearance is 2.4 meters. Transparency and lightness are characteristics of all three proposals. These traits assist the integration of this large structure into the traditional urban fabric.
1989 - 1996
6000 St. Gallen